Casting process and apparatus



FeB; 19,1929.

R. F. woon CASTING PROCESS AND APPARATUS Original Filed Aug. 7. 1919 5Sheets-Sheet 1 Feb. 19, 1929. A

' R. F. WOQD cAs'rme PROCESS AND APPARATUS Original Filed Aug. 7. 1919 5Sheets-Sheet INVENTOR 5050f F 5/001 A'ITDR Yd Feb. 19, 1929. Re. 17,220

R. F. WOOD CASTING PRocESs AND APPARATUS Original Filed Aug. 7. 1919 5Sheets-Sheet 3 INVENTOR Feb. 19,1929.

R. F. WOOD (TASTING PROCESS AND APPARATUS Original Filed Au;- 7. 1919 5Sheets-Sheet 5 1NVENTOR\\ YFaberZ A [1 006] l l \i BY v m mazs OriginalNo. 1, 88,780, dated April 14, 1925, Seria1 No. 315,892 filed August7,1919. Application as reissue med May 16, 1927. Serial No. 191,901. :1

Reissu d Feb. 19,1929.

UNITED STATES ROBERT E. woon, 0E NEWARK, NEW JERSEY, assrenoa cro THErArEa arExr'rLE MACHINERY COMPANY, OFSANDUSKY, OHIO, A-coRroRA'rmN or01110.

CASTING PROCESS AND APPARATUS My invention relates to an improvedprocess and apparatus for making castings of metal or of other-materialand is particularly applicable to the making of hollow or tubularobjects having non-cylindrical bores.

The object of my invention is the provision of a new and useful castingprocess. ()ther objects of my invention are; the provision ofapparatussuitable for carrying out my. process; the provision of aprocess whereby hollow or tubular castings may be produced without theuse of cores of sand or of other solid material; the provision of aprocess for producing a casting having a paraboloidal void, from whichcasting there may he made, by machining in a lathe or by.

other process of manufacture, a hollowaor tubular. article whose bore orvoid,. though not itself paraboloidal in shape, may be more or less}approximated in shape and size by the paraboloidal void of the casting;the provision of a process for producing castings for submarineperiscope tubes and cones and the provision of a centrifugal processwhereby a hollow or void of predetermined p-arab oloi dal shape may.beformed'in casting an object without theuse of solid. core,

'productionof submarineperiscope tubes and cones in which it isnecessary thatone end be of smaller diameter than theother, and

that the metal be of uniformly good quality free fromblow holesginternal strains and,

suchother imperfections as are common to tnhesfmade by certain othermethods of casting and manufacture. My invention: may

also be used for casting hollow projectile shells. I'do not limit theuses to whichm invention be put as numerouslapplications will occur tothose skilled in the various arts in which hollow or tubular parts'areused. In the accompanying drawingsI have illustrated one form" ofapparatus which has proved suitable for carrying out my process- In thedrawings, Fig. 1 is a side ellevation. of a" casting "machinesuitable[for carrying out my process; 1 n p Fig.2 is a'verticalfragmentary cross section through the upper endof'the mold on line 11-11of'Fig. 3; p 7

Fig. 2 is a similarview ofthe otherend of the mold showingfits stop-offplate; Fig. 3 is an endf'el'evation of" the front or axis while in: thisinclined. position.

making a metal castingt'hegmolten metal is Fig. 1;

or is t hand end of. the machine shown in Fig. .1

ing the theory of my process;

Figs. 9ito ll anclusiveare sections through p'araboloids generatedxbyparabolas of difierent equations and;

Figs. 18, I19 and 20. are longitudinal cross= sections of variouscastings suitablefor maklng submarlne perlscope tubes. I

In carrying out my process I introduce a l quantity of molten metal orof other solidifiable material into a hollow mold of metal 1 or ofsuitable refractory material, :the quan-.

tity of molten metal. being insuificientto-fill the mold. The Inoldispreferably first in,

clined so that, its axis makes a knownuangle with the horizontal, and isgiven ia rapid:

rotating motion of known .speedaboutits introducedintogt-he moldpreferably whileit is rotating. .Undenthe. action of centrifugal? forceand of, gravity -the'metal flows and My invention is particularly usefulin' the tation or at different angles of inclinationof the axis of themold, or both,- bores or voids of difierent shapes are formed in themolten metal. I have, discovered and demonstrated, 1

however,= that the. shape of the hollow or void formed in the liquid ormolten material is independentof the shape ofthe mold and is always aparaboloidpf revolution. or some part thereof, the shape and dimensionsof which are determined the size'of the mold,

its speed. ofrotation, the. angle of inclination of the axis of rotationand-,thequantity of metal in the mold. I have proved mathematicallyandhave demonstrated in practice by making. numerous castings that thereare a definitely. filxed relations between these factors; that the shapeand dimensions ofthe hollow orloore in a;casting mayi becalculated inadvance for any givensize of'mold, speed of rotation angle of1ncl1nat1on, and

quantity of metal; and that when the size of the mold and the essentialdimensionsof the required holl'ow or bore are given, the

speed of rotation of. the mold, its angle of inclination, the quantityof metal to use and the'shape of bore that will result may bepredetermined by calculation. I

It is to be understood that in these specifications the term inclined orinclination comprises any position other than horizontal up to andincluding ninet degrees where the axis of the mold would e vertical.

In carrying out my process, the s eed of rotation of the mold and theangle 0 its inclination, or both, may remain constant throughout theentire period of pouring, casting and solidifying, but I do not considerthat this is essentialin all cases. It is evident that in order toproduce a simple paraboloidal void of predetermined shape, the metalmust be maintained in a state of equilibrium while it passes from themolten to the solid condition, and this state of equilibrium is by thattime a Is to be used would boloidal shape of the which is sti mostreadily obtained, by keeping the speed of rotation and the angle ofinclination constant. However, it is conceivable that there might ariseconditions under which the process by which the rou h casting issubsequently to be treatedor t e purpose for which it be better servedif the casting process were so controlled as to modify more or less theotherwise simple parabore of the casting. It is furthermore evident thatif the speed or angle be changed at a moment when the process ofsolidification of the metal is as yet incomplete, the ortion of themetal which has ready become solidified will retain its position inspite of such change in speed or angle, while the portion of the metal 1molten or semi-molten will flow or tend to flow in such away as toreadjust itself to the new conditions, and, under them,

i to reacha new position and a new state'of 'equillbrium. In myexperience witln the practical carrying out m process I have alreadencountered con itions such as I have escri'bed, and I have encounteredinstances in which the subsequent processes of machining the casting ina'lathe were facilitated by having the otherwise simple paraboloidalshape of the bore of the casting modified in accordance with theforegoing. It is, therefore, conceivable that other instances also mayarise in which the purposes or treatment, of the casting will be .betterserved by the modifications described or by other modifications similarthereto, and it is one of the advantages of my process that in practiceit allows of such modifications and that the modifications admit, ofcontrol because the limits of their action and effects may bepredetermined by calculation by means of the equations and formulaswhich I have derived or by others deducible therefrom. f With thepurpose in view of making castings for submarine periscoge tubes andcones I first discovered by mat ematical calculations thatthe shape ofthe hollow or vold formed in liquid material rotating in equilibriumabout an inclined axis is, that of a paraboloid of revolution such as isformed by the rotation about its own axis of a parabola the equation ofwhich may be expressed in terms of the speed of rotation of the li uidand the angle of inclination of the axis 0 rotation. With this factestablished I deduced certain other equations which establish therelations between the speed of rotation, the angle of inclination of theaxis of rotation and the shape of the paraboloid formed, from whichequations the requirements for producing any desired casting which it ispossible to produce b my process can be determined. I have ca culatedthe shapes and dimensions of many castings by the nations which areherein given and have su s'equently made castings in strict accordancewith the conditions'imposed by my calculations. I have found in everyinstance that the actual castingsproduced conformed with. remarkabletrueness to my advance calculations. V

In Figs. 1, 2,.3 and 4 there is shown amachine which I have foundsuitable for carrying out my process. .In these figures of the drawings,1 representsa revoluble metal pipe or tube which is provided withsuitable bear-, ing collars 3, 4, located near its front and upper end5. A tilting housing 6 which has trunnions 7 supportedin hearings in thesides of the station ry frame 8 is provided for the sup port of the tube1 and its driving motor. Radial-thrust rollers 9 for rotatablysupporting tube -1 are provided in'the tilting housing 6.

ployed for rotating the tube 1 and that any convenient means may be usedfor ascertainin and controlling the speed of rotation.

ear the rear end of the tube 1 which is also the lower end when the tubeis tilted, is the stationary frame or guide 14 in which there is mountedand adapted to slide vertical ly a housing 15, which is provided withradial thrust rollers 16 upon which the tube 1 lo tates. i v

The uppermost rollers 9 and 16 have bearings in spring-held, adjustableboxes 17 and 18, the springs 19 and 20 serving to maintain the rollerswith yielding pressure upon the rotating tube 1. The housing 15' isprovided with trunnions 21 which are adapted to slide in slots 22 in theguides 14. Attached to the. trunnions 21 by pivoted "collars 23 are thecables 24-. which extend upwardly and are connected with a device 25 forraising and lowe'ring the rear end of the tube 1 in order to tiltthe-tube to the desired angle. To give added rigidity and added accuracyof setting to a known angle, holes such as 26 may be drilled through thesides of the guides 14 and the rear housing 15 and in like-mannerthrough the sides of the stationary frame 8' and the front housing 6 insuch manner as to receive throu h-bolts such as 27 with nuts which,

when drawn tight, serve to secure the several parts of the constructionin perfect alinement in their inclined position.

The tube 1 is either lined with refractory material such, for instance,as a sand mold of annular cross section or, preferably, as shown 1n Fig.2, receives a pipe or tube v.28 having a.

refractory lining 29, the opening in the refractory liningbeing of theshape which it is desired to give to the exterior of the casting to bemade therein... 1 i

The back or lower end .of the mold is formed by a stop-off plate or plugA shown in Fig. 2*, set at the desired distance from the front end ofthe mold so as to determinethe length of the casting and secured inplace by a rod B that extends between it and yoke device 30. The frontvor upper end of the mold is formed by an annular disk or plate of metal31 which is secured to the flanged end of-the tube 1 by means of bolts32 and which may receive a lining or facing 33 of refractory material.

In the operation of the machine to produce a. casting by my process, thetube 1 has first inserted into it thepipe 28 with its refractory lining29 which has been preheated to drive off the moisture that it may havecontained. The tube 1 is then tilted to the proper angle for producingthe desired casting, for instance, the angle at which the tube is shownin dotted lines at 34. The tube 1 with the pipe and its refractorylining are next brought to thedesired speed of rotationby means of themotor 12 or by any other means that. may be providedfor the purpose, themolten metal is then introduced through the opening 35, at the upper endof the moldand is disposed by centrifugal force andlg ayity into theshape which it is made to assume by these forces.

The rotation is preferably continued until the metal has solidified.

The mold as is then reihqvdffiomthe tube 1 and the castin afterwardsremoved from the mold. It is t en ready for .machining or othertreatment, or for use in its rough condition. Another prepared mold. isthen inserted in the tube andthe operation repeated. e Fig. 18 shows inlongitudinal section. a

casting suitable for making the separate cone of a submarine periscopetube. In this figure the scale of the drawing parallelto the axis of thecasting is made much smaller than the transverse scale for the purposeof illustra tion.

Fig. 19 shows in longitudinal section a casting suitable for making asubmarine perior stop-ofi' end 38 is of another formed in the castingshown in Fig. 20 is the resulting composite of a plurality ofsuccessively formed paraboloids.

In Flg. 18 the refractory material of the mold is indicated at 39 by thearea'shaded in dotted section lines; the casting itself 40 is indicatedin section; theparaboloidal bore formed inthe process of casting isindicated bythebou'ndarylines 41"anid the outline of thefinished'cone'which is machined all over is indicated in dotted lines at42. 1

In Fig. 19 the material o'f the refractory mold is shown in dottedsection lines at 43; the casting itself is indicated in section at 44;the paraboloidal void in the casting is indicated by the boundary lines45 and the finished tube is indicated in dotted lines at 46.

In Fig. 20 the material of the refractory mold is indicated in dottedsection lines at 47 the casting is indicated in section at 48; the upperportion of the paraboloidal void is indicated by the boundary lines 49extending between the up er end 36 and the point 37 of the casting; l feportion of the paraboloidcorresponding to theboundary lines 49 whichwould be formed evcept for the changing of the angle of inclination orof the speed of rotationor both during the process of casting is shownby the dotted extension 50 of lines 49 the virtual vertex of theparaboloid corresponding to the boundary 49, 50 is indicated at 51; theparaboloidal void formed after changing the angle of inclination or thespeed of rotation, or both, is indicated by the boundary lines 52extending from the point 37 to the vertex 53 and the finished tube to bemachined out of the castin" 48 is shown in dotted lines at 54.

in Figs. 19 and 20 the longitudinal scale of the drawings is made muchsmaller than clination of its axisor the proper angle of inclination ofthe mold for any given speed of rotation, and the quantity of metalrequired to form the casting.

The void formed in liquid material rotating about an inclined axis ina'mold or receptacle having. its

bottom closed and its top closed as shown in Fig. 2 to within asufficient radial distance from the axis of rotation to prevent theegress of the liquid is as follows:

Referring to Fig. 5, let A be any particle of molten metal or. of otherliquid material in the inclined mold, the angle of inclination of theaxis Y of the mold with the horizontal being S. Let theweight of theparticle be G pounds. Let P and Q be the components of G in directionsrespectively parallel to. and at right angles to the axis of the moldand in a vertical plane through the axis. Under these conditions P=G sinS. The force Q may be disregarded in the present consideration becausewhen the mold an the particle A revolve, the action of Q toward the moldbecomes in each revolution alternately and equally positive and negativeso that Q, compensates itself relative to the mold and does not affectthe position which the surface of the molten metal will assume withinthe mold. It may be noted here that Q is the force which determines theminimum speed at which the mold must be revolved in order to hold themetal against the sides of the mold. Considering the particle A, it willreadily be understood thatwhen A and the mold are revolving, the forceQ, must be overcome by the centrifugal force when A is at the highestpoint of its revolution in order that the particle may be prevented fromfalling away from the upper side of the mold.

t us now consider the forces which act upon the particle A afterequilibrium has been established and while the mold and A are rotated atconstant speed about the inclined axis of the mold. A diagram of theseforces is shown in Fig. 6.

Referring to Fig. 6, as the machine and the particle A revolve, A isacted upon by two forces which together determine the shape assumed bythe surface of the molten metal.

. These two forces are P and the centrifugal force C. Their resultant isthe force N whose direction, if the particle A be at a point in the theproper speed of rota- I tion of the mold for any given angle of inproofof the shape of th e hollow or known and without surface of the metal,must be normal to the surface at that point. Therefore, a -line drawnthrough the point A at right angles to the direction of the force N, andin the plane determined'by the point A and the axis of rotation, asshown in Fig. 6, must be a tangent to the curve that is formed by thesurface of the metal. This tangent will make an an le T with thedirection of the axis of the mol From the construction, r

. P tan T-- I As 0 is the centrifugal force,

where M is the mass of the particle A, '0 its velocity in feet perrotation in feet. tion for the value p and 0 found above gives e Sill 'sG i sin s.

Substituting in the equatan T= L M M0 r Since or the acceleration due togravity,

' an T=-";#

g r sin S g sin'S aTa ma; (1)

(1) may be found the angle or any inclination andany speed, butonly borewhen such are determining where those radii will be formed. I

In Fig. 7, let the axis of rotation be the axis Y, and X be itscoordinate axis. figure the point A is taken at (m, y), angles S and Tare the same as before. Fig. 6, the straight line drawn through (:v,y)is, under the conditions, the curve that forms the surface'of the metal,consequently the inclination of this line to the axis X must be theslope of the curve at (my), and that-slope is equal to the tangent ofthe angle H.

From the construction, 7"-?m.

From Equation T f for individual radii of the and the second and r theradius of of ten T the values of P Inthis As in Inn a, tangent to shownhe represented The following relation Y The difierential equation ofnowbe written and proves that the surface of the molten metal rotatingabout an inclined axis is a paraboloid of revolution such as would beformed by the rotation about itsaxis of the parabola of the aboveequation, (2)

From equation, (2), the curve for any particular case may be put intothe form y=aa1 the constant, a being equal to then for anyasslgned'value ofB or S a corresponding value must exist for Sor R. Itis evident, therefore, that theequationof the curve maybe madeindependent of both R and S, provided that other determining factorsaregiven. This maybe done as follows:

Referring to Fig. S'Qlet'the'parabOla there he equation y =a m twopoints (00 '11) this parabola 1 a i ,y. f=ee ?1e=. 1f By subtraction, s

say r, and T in the bore or void of the casting,

at two different points along its axis and ':l/ is the axial distancebetween them.

If L= y y, the last equation may be re- Equation (3) is the equation oftheparab 01a in terms of any two radii of the bore of the casting andthe, axial distancei betweenthose radii, and istheGQUEtlOIlQIIlOShCOIIl- L P v th s, the-follow ng volume formula maybe monly ,used' ,to determine the" shape of the bore. Equations (2) and,(3) are the main equations for the solution of the problems of" my thecurve may ld ftrue. for any g located on Now m, and 00 are identical totwo radii;

depends only upon the known factors or conditions which are given,fromwhich to find the remaining conditions necessary to successfullyproduce the casting in practice.

Derived equations showing relations between speed and inclination forany given parabola.

Solving (2) for wehave R=- 1.2755 li (4) This may be convenientlywritten R==1.2755,/a Sln s (5) Remembering also the value of (a) whichis used in Equation (3) we may write Equation (4) gives the revolutionsper sec- 0nd in terms of the sine of the angle of inchnation, any radiusof the bore expressed in feet, and the axial distance in feet of thatradius from the vertex of the parabola Equation (5) gives therevolutions per second in terms of the sine of the angle of inclinationand the coefficient a of m in the equation of the parabola, and is theequation most commonly used to obtain speed and-angle relations W p 1Equation (6) gives the revolutions per second in terms of the sineof-the angle of inclination, any tworadii' of the bore expressed a infeet, and thea-xial distance in feetbetween those radii:

Transposing (4), (5) and (6), gives the angleinterms -of the revolutionsper second, the other conditionscorresponding exactly to thoseenumeratedabove. The corresponding values for the-anglesfollow:

. R x .=s1n- (O.61463 y (-7) the mold. The volume-of the mold may befound by addingtogether the volumes of its "arts; If the'frustum'ofacone enters into used '2' h sew bases, his the altitude'ofthe frustumand 4 d, and

- these equations to 1 the required tube d, are the diameters of the twobases respectively. n

The volume of the voidwill be the volume of so much of the paraboloid asis contained between the front and back ends of the mold. The positionof the vertex of the paraboloid relative to the back end of the mold ispreferably to be first known and may be found by makingsthe propersubstitutions in Equation (2) or quation 3) or, better, directly in theequation y=aw after (a) is known.

If V represents the volume of the paraboloid between the front and backends of the mold when the vertex lies behind the back end of the mold,then 1 .5 O Y Z 6 12 -101 If the vertex lies within the mold, y, becomeszero and To illustrate the practical application of the determination ofthe conditions that should be observed in maki a casting by'my process,I herein show the 'solution of a concrete case such as might occur inractice. I

eferring to Fig. 19 of the drawings, let it be reglnired to provideacasting from which to m e a submarine Periscope tube such as is shownin dotted outline and longitudinal section at 46. Let the finisheddimensions of inches at m, and 6% inches at n and over all length 14feet, for 10 feet of which, from o to n, the tube is the remaining 4feet, from n to m, uniformly tapered; wall thickness, inch. In order toproduce a finished tube conforming to these measurements, let there berequired a rough casting such as is indicated at 44 in Fi 19, of thefollowing dimensions: outside iameter 4 4 inches at p and m, and 6%inches at n, o and 9; inside diameter 2% -inches at p,

and 5 inches at g; over-all length 14 feet this 6 inches, of which 14feet is the length of the finished casting, 2 inches an extra allowancein length at the small end p, and 4 inches an extra allowance in, lengthat the large end 9.

Examination of the data discloses that for casting the measurementsgiven are reucible to the requirements of Equation (3), viz, two radiiof the bore and the axial distance between them. Expressed in feet theradii of the desired inside diameters, 2% and 5 4 inches res ectively,will be w,=0.1146 ft and w '=0.218 ft., and the length L of the castingequals 14.5 ft. Introducing these values into equation (3) be: outsidediameter 4 to be cylindrical, and for.

which, if revolved about its axis would enerate a paraboloid, part ofwhich would be of the shape and size of the bore which would be obtainedin the rou h casting.

It now remains to fl x the sped and angle relations, which may be donethrough either Equation ('5) or (8). If the angle of inclination beassigned, Equation (5) will determine the speed of rotation while if thespeed of rotation be assigned, Equation (8) will determine the angle ofinclination. In either case the value of a 418, as found above, willalso be used. Accordingly if the assigned angle of inclination be 10degrees, its sine, 0.1736, and the value 418, found for a, may besubstituted in Equation (5), yielding R=,1.275 51/418X0.1736, whence R,the revolutions per second equals 10.87 and the revolutions per minuteequals Whence S=827, which would be the mold inclination correspondingto a speed of rotation of 600 revolutions per minute.

To determine the volume of the mold, the

volume of the parts may be determined sepor S sin"0.14704 arately andthen added together:

- I Cubic inches. 11 to m (cylinder) 28 m to n (frustum of cone) .1160nto g (cylinder) 4437 Total volume of'mold 5625 To'determine the volumeof the bore of the casting, Equation (11) may be used. The values of y,and y, may be found by substituting back into y=418 as the values bf w,and :27, already used, 0.1146 and 0.2187 respectively. Accordingly,

the speed of rotation cor- It may be noted here that y,, or 5.5 feet is,v I

the distance from the back or smaller end of the casting to the virtualvertex of the paraboloid, as from p to'55 in Fig. 19, and that havingfound it, the value of 3 may be determined by addin to it L, or 14.5feet, giving 20.0 feet, whic is identical, as it should be, to the valueobtained by substitution,

From these values, and" the value of a, by Equation (11).,

ent:

mold revolubly tained by point, obviously,

' and said housing.

4. In apparatus of the class described, a

This is in cubic feet, and is cubic inches. I

To determine the quantity of metal in the rough casting,its volume mayfirst be found, and then its weight. Its volume may be obfinding thediiference between the volumes of themold and of the bore, 5625 and2401-cubic inches respectively, or 3224 cubic inches. If the weight percubic inch of equal to 2401 the metal employed be 0.30pound, theweightof the casting would then be 3224 times 0.30 pound, or 967 pounds. f

the specific gravity of In using my process the material cerns therelations of the bore of the casting. num, lead, or any other substancebe used, 1s, therefore, a matter of indifference everywhere in thecomputations, except only in theoperation of deducing the weightof-thecasting from the value found for its volume, at which a} correct valuefor the weight per unit of substance should be used.

The proof that these relations and the; equations representing them arethus independent of the specific gravityof the material is seen in thederivation of Equation (1) where the mass, M, of the particle, has beenshown to disappear.

Having thus described my invention, I claim and desire 1. In apparatusand: the like having parabolo'idal hollow bores, a mold the interior ofwhich has the desired form of the exterior of the casting, means forrotating said mold at the requisite speed and means for giving to theaxis of: said mold the requisiteinclination to produce within thecasting a cavity of the desired paraboloidal form. f r

,3. In apparatus for casting metal tubes and the like havingparaboloidal hollow bores formed under the joint action of centrifugalforce and gravity, a revoluble mold, a support therefor, bearingsdgrsaid revoluble mold carried by said'support, and means for revolvin saidmold, the axis of rotation of said mol being inclined to thehorizontal.

3. In apparatus of the class described, a mounted in a tilting housing,a motor mounted on said tilting housing, driving connections betweensaid motor and said mold, and means for tilting said mold mold revolublymounted in a housing, a support for said housing, a. motor mounted onsaid housing in driving connection with said mold, and means for tiltingsaid mold and said housing.

5. In apparatus of theclass described two stationary supports, a tiltinghousing mountfromw'hich acasting is to be made is'a matter of i"difference so far as conbetween the speed of rotation, the angle ofinclination, andthe shapef Whether alumi i to secure by Letters Pat-'for casting metal tubes ed on one of said supports, a verticallyadjustable tilting housing mounted upon the other ofsaid supports, and arevoluble mold carried in bearings in said housings.

6. In apparatus of the class described, a stationary support, a tiltinghousing mounted on said supportfa vertically adjustable tilting housing,a ,revoluble mold carried in bearings in said housings, and means forrotating said mold. i

7. In apparatus of the class described, a stationary'support, a tiltinghousing mounted on said support, a vertically adjustable tiltinghousing, a revoluble mold carried in hearings in said housing, means forrotating said mold about its axis and means for inclining said'axis ofsaid mold. stationary support, a tilting housing mounted upon saidsupport, a vertically adjustable tiltinghousing, arevoluble mold car- 8.In apparatus of the class descrbed, a

ricd in bearlngs in said housings, means for rotating said mold aboutits axis, means for inclining said axis of said mold, and means forsecuring said vertically adjustable housing in its adjusted position.

9. In apparatus f the class described, a

revoluble mold, two bearings for said mold,

one of said bearings being mounted for tilt:

ing'about an axistransverse to the axis of rotation of said mold and theothenof said bearings being mounted for tilting about an axis transverseto the axis of rotation of said mold, and means for vertically adjustingone of said bearings. a

10. In apparatus of the class described, a revoluble mold, two bearingsfor said mold, both. ofsaid bearings beingprovided with trunnions havingtheir axes transverse to the axis of rotation of said mold, one of saidterial which consists of placing a quantity 3 of said fluid material ina hollow mold, the volume of said fluid material being insufi'icient tofill said mold, imparting a rotating movement to the fluid material insaid mold whereby a paraboloidal void is formed in said material aboutthe axis of rotation thereof, continuing the rotation of the material inthis position until a portion-of the material is solidified, theninclining the axis of rotation from the position it tained andcontinuing the rotation of the material until another portion of it hassolidified; i

as thus far mainternal cavity of said shell mold coinciding, said 13.The processof forming hollow tubular objects which consists of impartingto a quantity of solidifiable fluid material a rapid so that it formswithin such limits a hollow shell of non-uniform inside diameter, theinbeing a parabolold symmetrical with the axis of rotation,- continuingthe rotation of the material about said inclined tation'of. the materialuntil another portion of it is solidified. V I The process of'forminghollow tubular objects which consists of imparting to a quantity ofsolidifiable fluid material a rapid rotatin movement about an axis,confining the s ai material within radi al limits but uniform diameter,the" internal cavity of said shell being a paraboloid symmetrical withthe axis of rotation, continuing said rotation at a constant speed untila portion of said material is solidified, then changing the speed ofrotation andcontinuing it at said changed speed until another portion ofthe material has solidified, 15. The method of making periscope tubes orthe like of cast metal which consists of centrifugally casting a longparaboloidal void in a metal cylinder the contour of the longitudinalcross section of said void approximatingthe desired contour of thefinished tube with allowance for internal finish, and subsequentlyfinishing the inner surace to the desired dimensions and contour. 16. Icasting machine, a shaft, bearings supporting said shaft, saidbearingsbeing adjustable to incline the axis'of said in said shaft," the axis ofsaid shaft and said shaft and said mold means for said shaft.

' ta'table hollow shaft pivoted shaft, a hollow mold being open'at theirupper ends, and driving a centrifugal casting machine, a revolublehollow shaft, bearings supporting said shaft, said bearings beingadjustable to incline the axis of said shaft, a hollow mold in saidshaft, the axis of said shaft and said mold coincidin said shaft andsaid mold being open'at t eir upper ends, and driving means for saidshaft operable to drive the same in any of its adjusted positions.

' 18. In a centrifugal castin or tilting movement on an axis transversethereto and adjacent one end thereof, a housing arranged to tilt withsaid shaft, a motor on said housing operatively connected and a hollowmold in said shaft adapted to receive molten metal and to form a castingtherein.

19. In a centrifugal-casting machine, a ro tatable hollow shaft pivotedfor jacent the other end of the pivoted shaft for raisin and loweringthe shaft on its pivot.

20. n a centrifugal castin machine, a rotatable hollow shaft pivoted ortilting movement on an axis transverse thereto andad:

and. means adjacent the a casting therein, other end of the and loweringthe shaft on its'pivot.

witness whereof, I have hereunto set day of April, 1927.

my hand this 29th J ROBERT F. 'WOOD.

to rotate the shaft,-

plvoted shaft for. raising machine, a ro-

